Bulgarians have gone to the polls to elect the country’s new president as well as mayors, amid concerns over vote fraud and economic woes.

Some 6.9 million Bulgarians are eligible to cast their vote in the Sunday polls.

Opinion polls show that none of the 18 presidential candidates can be expected to win an outright victory and that the country would likely hold a runoff on October 30, the Associated Press reported.

The elections are held as Bulgaria’s economic woes are the major campaign issue, with the opposition accusing the ruling center-right party of not implementing key reforms in the European Union’s (EU) weakest economy.

Meanwhile, international observers have expressed concern over the possibility of widespread fraud in Sunday votes, a factor that can block Sofia’s bid to join Europe’s passport-free Schengen travel zone.

“There are fears about large-scale vote buying and manipulations in the counting of the ballots,” the Organization for Security and Co-operation in Europe monitoring team said.

Graft watchdog Transparency International has also warned that about 20 percent of the Bulgarian voters may be persuaded to sell their ballots.

Polls show that former Construction Minister Rosen Plevneliev is the most hopeful presidential candidate with about 30 percent of the vote.

Plevneliev, who is supported by the center-right ruling party of Prime Minister Boiko Borisov, has vowed to reduce Bulgaria’s budget deficit and adopt business-friendly policies.

In Bulgaria, the prime minister is considered the highest-ranking official, but the president controls the army and has the power to veto legislation and sign international treaties.